Sofa



FIG. 1 is a center, front perspective view of a design for a sofa;

FIG. 2 is a middle left, front perspective view of said design;

FIG. 3 is a top left, front perspective view of said design;

FIG. 4 is a right, front perspective view of said design; and,

FIG. 5 is a right, rear perspective view of said design. 

The ornamental design for a sofa, as shown and described. 